The role of glycodelin in cell differentiation and tumor growth

The pregnancy-associated protein glycodelin as a potential sex-specific target for resistance to immunotherapy in non-small cell lung cancer

Lung cancer has been shown to be targetable by novel immunotherapies which reactivate the immune system and enable tumor cell killing. However, treatment failure and resistance to these therapies is common. Consideration of sex as a factor influencing therapy resistance is still rare. We hypothesize that the success of the treatment is impaired by the presence of the immunosuppressive pregnancy-associated glycoprotein glycodelin that is expressed in patients with non-small-cell lung cancer (NSCLC). We demonstrate that the glycan pattern of NSCLC-derived glycodelin detected by a lectin-based enrichment assay highly resembles amniotic fluid-derived glycodelin A, which is known to have immunosuppressive properties. NSCLC-derived glycodelin interacts with immune cells in vitro and regulates the expression of genes associated with inflammatory and tumor microenvironment pathways. In tumor microarray samples of patients, high glycodelin staining in tumor areas results in an impaired overall survival of female patients. Moreover, glycodelin colocalizes to tumor infiltrating CD8+ T cells and pro-tumorigenic M2 macrophages. High serum concentrations of glycodelin prior to immunotherapy are associated with a poor progression-free survival (p < 0.001) of female patients receiving PD-(L)1 inhibitors. In summary, our findings suggest that glycodelin not only is a promising immunological biomarker for early identification of female patients that do not benefit from the costly immunotherapy, but also represents a promising immunotherapeutic target in NSCLC to improve therapeutic options in lung cancer.

The diversity of lipocalin receptors

Lipocalins are important carriers of preferentially hydrophobic molecules, but they can also bind other ligands, like highly polar siderophores or intact proteins. Consequently, they are involved in a variety of physiological processes in many species. Since lipocalins are mainly extracellular proteins, they have to interact with cell receptors to exert their biological effects. In contrast to the large number of lipocalins identified in the last years, the number of receptors known is still limited. Nevertheless, some novel findings concerning the molecules involved in cellular uptake or signaling effects of lipocalins have been made recently. This review presents a detailed overview of the receptors identified so far. The methods used for isolation or identification are described and structural as well as functional information on these proteins is presented essentially in chronological order of their initial discovery.

β-Lactoglobulin and Glycodelin: Two Sides of the Same Coin?

The two lipocalins, β-lactoglobulin (βLg) and glycodelin (Gd), are possibly the most closely related members of the large and widely distributed lipocalin family, yet their functions appear to be substantially different. Indeed, the function of β-lactoglobulin, a major component of ruminant milk, is still unclear although neonatal nutrition is clearly important. On the other hand, glycodelin has several specific functions in reproduction conferred through distinct, tissue specific glycosylation of the polypeptide backbone. It is also associated with some cancer outcomes. The glycodelin gene, PAEP, reflecting one of its names, progestagen-associated endometrial protein, is expressed in many though not all primates, but the name has now also been adopted for the β-lactoglobulin gene (HGNC, www.genenames.org). After a general overview of the two proteins in the context of the lipocalin family, this review considers the properties of each in the light of their physiological functional significance, supplementing earlier reviews to include studies from the past decade. While the biological function of glycodelin is reasonably well defined, that of β-lactoglobulin remains elusive.

A role of heparan sulphate proteoglycan in the cellular uptake of lipocalins ß-lactoglobulin and allergen Fel d 4

Lipocalins, small extracellular hydrophobic molecule carriers, can be internalized by a variety of different cells. However, to date receptors have only been identified for human lipocalins. Here, we specifically investigated uptake mechanisms for lipocalins ß-lactoglobulin and Fel d 4 in HeLa and Chinese hamster ovary (CHO) cells. We provide evidence that cell surface heparan sulphate proteoglycan is essential for internalization of these lipocalins. In HeLa cells, lipocalin uptake was inhibited by competition with soluble heparin, enzymatic digestion of cellular heparan sulphate by heparinase and inhibition of its biosynthesis by sodium chlorate. Biochemical studies by heparin affinity chromatography and colocalization studies further supported a role of heparan sulphate proteoglycan in lipocalin uptake. Finally, lipocalin uptake was blocked in CHO mutant cells defective in glycosaminoglycan biosynthesis whereas in wild-type cells it was clearly detectable. Thus, cell surface heparan sulphate proteoglycan represents a novel component absolutely participating in the cellular uptake of some lipocalins.

Decidual glycodelin-A polarizes human monocytes into a decidual macrophage-like phenotype through Siglec-7

Decidual macrophages constitute 20-30% of the total leukocytes in the uterus of pregnant women, regulating the maternal immune tolerance and placenta development. Abnormal number or activities of decidual macrophages (dMs) are associated with fetal loss and pregnancy complications, such as preeclampsia. Monocytes differentiate into dMs in a decidua-specific microenvironment. Despite their important roles in pregnancy, the exact factors that regulate the differentiation into dMs remain unclear. Glycodelin-A (PAEP, hereafter referred to as GdA) is a glycoprotein that is abundantly present in the decidua, and plays an important role in fetomaternal defense and placental development. It modulates the differentiation and activity of several immune cell types residing in the decidua. In this study, we demonstrated that GdA induces the differentiation of human monocytes into dM-like phenotypes in terms of transcriptome, cell surface marker expression, secretome, and regulation of trophoblast and endothelial cell functions. We found that Sialic acid-binding Ig-like lectin 7 (Siglec-7) mediates the binding and biological actions of GdA in a sialic acid-dependent manner. We, therefore, suggest that GdA, induces the polarization of monocytes into dMs to regulate fetomaternal tolerance and placental development.

Influence of VEGFR and LHCGR on endometrial adenocarcinoma

Endometrial adenocarcinoma is a common gynecological malignancy that is usually treated by surgical resection followed by radiation. However, the frequency of remote metastasis is high. The present study aimed to investigate whether patients with endometrial adenocarcinoma exhibited a positive response to treatment with a gonadotropin-releasing hormone analogue or inhibitors of neoangiogenesis, which are applied for the treatment of other malignancies. Immunohistochemical analyses were performed using 203 paraffin-embedded tissue samples of endometrial adenocarcinomas from patients who had undergone surgery at the Department of Obstetrics and Gynecology of the Ludwig Maximilians University of Munich, Germany. The tissues were incubated with antibodies against luteinizing hormone/choriogonadotropin receptor (LHCGR) and vascular endothelial growth factor receptor 2 (VEGFR2), and evaluated by bright field microscopy. The staining was categorized according to the Immune-Reactive-Score (IRS). The IRS scores were then statistically associated with various tumor traits, including tumor size, lymph node status, metastasis, grade, expression of steroid hormone receptors and patient survival. There was a significant association between VEGFR2 expression and tumor grading and estrogen receptor-α (ERα). For LHCGR, a correlation was observed with ERα and progesterone receptor (PR). No correlations were identified between VEGFR2 or LHCGR expression and the other examined tumor traits or patient survival. The associations between VEGFR2 and ERα, and between LHCGR and ERα or PR, may be explained by the interaction of these signal transduction molecules in the regulation of cellular growth and differentiation. These mechanisms also have an important role in the formation of remote metastases, which is the main cause for tumor-associated mortality. The results of the present study suggested that patients with endometrial adenocarcinoma may benefit from treatment with inhibitors of ERα, PR, VEGFR2 or LHCGR, since it could lead to a better prognosis. However, further studies are required in order to elucidate the roles of these receptors in endometrial adenocarcinoma.

A systematic analysis of human lipocalin family and its expression in esophageal carcinoma

The lipocalin proteins (lipocalins) are a large family of small proteins characterized by low sequence similarity and highly conserved crystal structures. Lipocalins have been found to play important roles in many human diseases. For this reason, a systemic analysis of the molecular properties of human lipocalins is essential. In this study, human lipocalins were found to contain four structurally conserved regions (SCRs) and could be divided into two subgroups. A human lipocalin protein-protein interaction network (PPIN) was constructed and integrated with their expression data in esophageal carcinoma. Many lipocalins showed obvious co-expression patterns in esophageal carcinoma. Their subcellular distributions also suggested these lipocalins may transfer signals from the extracellular space to the nucleus using the pathway-like paths. These analyses also expanded our knowledge about this human ancient protein family in the background of esophageal carcinoma.

Glycodelin A is a prognostic marker to predict poor outcome in advanced stage ovarian cancer patients

BACKGROUND

Glycodelin is a cell surface glycoprotein offering a unique gender specific carbohydrate configuration. Sialylated carbohydrate structures, which are unusual for mammals, characterize Glycodelin isolated from amniotic fluid (Glycodelin A, GdA). Glycodelin in general exerts multiple, partly opposing functions ranging from immunosuppression to cell differentiation. As these markedly influence tumorigenesis, this study aimed to clarify whether expression of different Glycodelin isoforms is related to clinicopathological characteristics and prognosis of ovarian cancer patients. Further the use of Glycodelin as a serum marker in benign and malignant ovarian diseases was evaluated.

METHODS

Ovarian cancer specimens (n = 152) were stained for Glycodelin with carbohydrate and peptide specific antibodies. Associations between Glycodelin expression and histological grading, FIGO stage as well as patient's prognosis were examined. Glycodelin was correlated to expression of gonadotropin receptors and mucin-1, which are discussed as ovarian cancer tissue markers. In addition, Glycodelin serum concentrations were analyzed in patients suffering from benign (n = 73) or malignant (n = 38) ovarian neoplasias.

RESULTS

Glycodelin A was found to be an independent prognostic marker for poor prognosis in advanced ovarian cancer patients. GdA staining correlated with gonadotropin receptor (FSHR and LHCGR) and with hCG expression. Gd expression showed a positive correlation with a tumour-associated epitope of mucin 1 (TA-MUC1). Further, compared to ovarian cancer, serum Gd was increased in patients with benign ovarian tumors.

CONCLUSION

Glycodelin A might be related to tumor aggressiveness and poor clinical outcome in advanced epithelial ovarian cancer. Glycodelin serum levels found in patients suffering from benign ovarian tumors, might contribute to a more global attenuation during progression of these precursor lesions.

BRAF mutation is rare in advanced-stage low-grade ovarian serous carcinomas

Low-grade ovarian serous carcinomas are believed to arise via an adenoma-serous borderline tumor-serous carcinoma sequence. In this study, we found that advanced-stage, low-grade ovarian serous carcinomas both with and without adjacent serous borderline tumor shared similar regions of loss of heterozygosity. We then analyzed 91 ovarian tumor samples for mutations in TP53, BRAF, and KRAS. TP53 mutations were not detected in any serous borderline tumors (n = 30) or low-grade serous carcinomas (n = 43) but were found in 73% of high-grade serous carcinomas (n = 18). BRAF (n = 9) or KRAS (n = 5) mutation was detected in 47% of serous borderline tumors, but among the low-grade serous carcinomas (39 stage III, 2 stage II, and 2 stage I), only one (2%) had a BRAF mutation and eight (19%) had a KRAS mutation. The low frequency of BRAF mutations in advanced-stage, low-grade serous carcinomas, which contrasts with previous findings, suggests that aggressive, low-grade serous carcinomas are more likely derived from serous borderline tumors without BRAF mutation. In addition, advanced-stage, low-grade carcinoma patients with BRAF or KRAS mutation have a better apparent clinical outcome. However, further investigation is needed.

BRAF mutation is rare in advanced-stage low-grade ovarian serous carcinomas

Low-grade ovarian serous carcinomas are believed to arise via an adenoma-serous borderline tumor-serous carcinoma sequence. In this study, we found that advanced-stage, low-grade ovarian serous carcinomas both with and without adjacent serous borderline tumor shared similar regions of loss of heterozygosity. We then analyzed 91 ovarian tumor samples for mutations in TP53, BRAF, and KRAS. TP53 mutations were not detected in any serous borderline tumors (n = 30) or low-grade serous carcinomas (n = 43) but were found in 73% of high-grade serous carcinomas (n = 18). BRAF (n = 9) or KRAS (n = 5) mutation was detected in 47% of serous borderline tumors, but among the low-grade serous carcinomas (39 stage III, 2 stage II, and 2 stage I), only one (2%) had a BRAF mutation and eight (19%) had a KRAS mutation. The low frequency of BRAF mutations in advanced-stage, low-grade serous carcinomas, which contrasts with previous findings, suggests that aggressive, low-grade serous carcinomas are more likely derived from serous borderline tumors without BRAF mutation. In addition, advanced-stage, low-grade carcinoma patients with BRAF or KRAS mutation have a better apparent clinical outcome. However, further investigation is needed.

Glycodelin expression associates with differential tumour phenotype and outcome in sporadic and familial non-BRCA1/2 breast cancer patients

Glycodelin (encoded by PAEP gene) is a secreted lipocalin protein mainly expressed in reproductive tissues, but also in several tumour types. In the breast, glycodelin is expressed both in normal epithelial and cancerous tissue. To investigate the association of glycodelin with clinicopathological features of breast cancer and outcome of patients we evaluated the protein expression of glycodelin in a large series of breast tumours. Immunohistochemical analysis of tissue microarrays was used to study glycodelin expression on 399 sporadic and 436 familial non-BRCA1/2 tumours with strong family history. Gene expression analysis was used to define genes co-expressed with PAEP in sporadic and familial non-BRCA1/2 breast tumours. In the sporadic series, the glycodelin expression associated with low proliferation rate (P < 0.001), with a tendency towards well-differentiated tumours (grades 1 and 2, P = 0.012) and high cyclin D1 (P = 0.034) expression. However, in familial non-BRCA1/2 cases with strong family history glycodelin expression associated with a less favourable phenotype, i.e. positive lymph node status (P = 0.003) and HER2-positive tumours (P = 0.009). Moreover, the patients with glycodelin-positive tumours had an increased risk for distant metastases (P = 0.001) and in multivariate analysis glycodelin expression was an independent predictor of metastasis (hazard ratio (HR) = 2.22, 95% confidence interval (95% CI) = 1.22-4.03, P = 0.009) in familial non-BRCA1/2 breast cancer. Gene expression analysis further revealed different gene expression profiles correlating with the PAEP expression in the sporadic and familial non-BRCA1/2 breast cancers. Our findings suggest differential progression pathways in the sporadic and familial non-BRCA1/2 breast tumours expressing glycodelin.